Cloud storage api for apps

I use Dropbox as my cloud storage provider.  There are a few free close storage providers.  On top of that, individual apps, like Evernote, tend to have their own cloud storage infrastructure.  Lately, I have been experimenting with storing the save game data for emulators on my Dropbox.  I have it working on Windows and Linux, but not Android.  It would be nice if there was one generic cloud storage api that all the apps could use.

My fear is that static software is turning more into "software as a service".  If the software is tied to its own cloud storage and the company goes under, the software stops working.  If the software uses a cloud storage api, then the software will remain usable.  Also, people tend to have multiple devices.  If I play a game on one device, I would like the saved progress to be available on all of my devices.  Right now, of an app wants to support this feature, they have to roll out their own cloud storage solution.

I would like to have a single cloud storage provider.  If I use Evernote too much, then I have to pay both Evernote and Dopbox.  I also want more apps to be "cloud enabled".  Dropbox just released an api that is specific to them.  That is a great first step.  Once other cloud storage providers do the same thing, someone can work on a single api that works for all storage providers.